In general, a microspeaker includes a magnetic circuit, a coil vibrating due to a mutual electromagnetic force with the magnetic circuit, and a diaphragm to which the coil is attached, the diaphragm vibrating with vibration of the coil and emitting sound.
In vibration of the coil, the diaphragm does not always vibrate in a desired direction, i.e., in a direction perpendicular to the diaphragm, but biased vibration or split vibration occurs, which leads to sound distortion. Thus, a suspension or the like is further provided between the diaphragm and the coil to solve the foregoing problem.
However, as high power is required for the microspeaker, there is an increase in factors causing biased vibration or split vibration, such as the increase in the overall height of the coil, the increase in amplitude, or the like. Therefore, additional structural changes are required to prevent the biased vibration or split vibration,
FIG. 1 is a view showing a conventional microspeaker which further includes an edge part at a lower portion of a suspension. A microspeaker disclosed in U.S. Pat. No. 9,210,511 includes a lower edge part (sub-side diaphragm) at a lower portion of a suspension, in addition to a dome part (center diaphragm), an upper edge part (side diaphragm) and the suspension, to prevent sound distortion.
However, the lower edge part is integrally formed in a ring shape, like the upper edge part, and the upper edge part and the lower edge part are coupled to form an air pocket. This air pocket raises heat in the diaphragm, which is disadvantageous for the high-power speaker, and increases the rigidity of the whole acoustic system, which leads to reduction of a sound pressure level (SPL). In addition, the air inflow is not smooth between the upper edge part and the lower edge part, which causes deformation of the diaphragm in vibration.